Descaling burner



c. MOTT ET AL 7 2,532,567

DESCALING BURNER Dec. 5, 1950 Filed Aug. 7, 1945 3 Sheets-Sheet l k N INVENTORS CHESTER MOTT ATTORNEYS Dec. 5, 1950 c. MOTT ETAL 2,532,567

DESCALING BURNER CHESTER MOTT ALFRED E CHOU/NARD BvITCI-IELL ,4- TYLUTKI 10am, WJM

'74 ATTORNEYS Dec. 5 1950 c. MOTT ETAL 2,532,567

DESCALING BURNER Filed Aug. 7, 1945 3 Sheets-Sheet 3 INVENTORS CHEJTER' MOT? ALFRED E CHO IVARD MITCHELL A. T UT/f/ BY Ma MfM ATTORNEYS Patented Dec. 5, 1950 UNITED STATES OFFICE (01. sea-9) 1A Elaim's. 1

This invention relates to blow pipes-or burner apparatusoi the type designed and adapted for producing a row of closely spaced high temperature flames for the heat treatment of a surface, as for example, to remove scale, rust or other adhering material from such a surface, or to change such material into easily removable form. Such a burner may, for example, be used in descaling metal blooms in preparation for rolling, or it may be used to remove rust from any metal surface to prepare said surfaceior painting.

As a feature of the present invention, the burner is mounted on a portable wheeled carriage adapted to be rolled over the surface to be treated. This burner carries a series of tips properly spaced; the proper positioning of these tips and their correct angle with respect to the workpiece being assured by the carriage meanting the burner.

a further feature, :the burner comprises a manifold head having a series of tips easily re movable for replacement and cleaning. These tips are desirably made of metal having high heat conductivity, such as copper, are all of the same size and shape as to be interchangeable, and are comparatively long. The relatively long distance that the gas travels in these tips irons out the turbulences in the gas, and results in a smooth gas flow, so that stable flame cones are generated. These comparatively long tips also serve to maintain the burner head away from the surface to be heated, and from the'intense heating zone created near the surface, so that destructive overheating of said head is prevented.

Moreover, these long copper tips aid in keep: ing the burner cool because of the large surface areas exposed to the air, and as a result, these descale a great deal faster than burners hitherto proposed for this purpose.

As a further feature, the burner head has a series of air passages with discharges on opposite sides of the -row of tips, and has means for delivering air under pressure to these passages. The airsu-pplythrough these passages aids in cooling the burner, and the ejected streams, as they are projected against the surface being heat treated, help to remove the scale which was loos.- ened; These air streams blow the scale away from the tips, and help prevent them from be coming clogged with the scale and dirt.

The volume of acetylene used in the-burner is relatively so that it {is diflicult to produce a good mixture, using the laurner manifold head as agas mixer. As another feature, there is provided a distributor block separate from .the :burner head, and a pair of :mixers connected :to said block for mixing the distributed gases. Thus a proper mixture of gases is obtained with less danger of backfiring .and flashback. Thermos mixers the gases, such as oxy n a 655 lene in proper proportions, and conduct them through tubes to the burner head. I

Various other features and advantages of the invention will be apparent from the follmy-ing particular description, and from an inspection or the accompanying drawings, in which:

Fig. 1. is .a side elevation of a descaling burner carriage assembly embodying the features of the present invention;

Fig. 2 is a top plan view of the lower pil ti n oi the assembly;

Fig. '3 is atop plan view of the gas distributor and mixer unit;

Fig. 4 is .a front elevation with parts broken away of the gas distributor and mixer unit;

Fig. 5 is a fragmentary. side elevation of the gas distributor and mixer unit;

Fig. 6 is a transparent diagrammatic perspective of the burner-manifold head show n the air conduit system;

Fig. 7 is a transparent diagrammatic perspective of the burner manifold head showing the conduit system for the ...combustible mixture of gases;

Fig. *8 is a fragmentary diagrammatic perspective of the burner manifold head showing how the flame tips are: attached thereto;

Fig. :9 is a front face view of the burner manifold head;

Fig. 10 is an end view .of the burner manifold head;

Figs. 11, 1-2 and 13 are transverse sections taken on lines ll-all, |2--l'2 and 13-43 of Fig. '9, respectively; and

Fig. 1a is a section taken along lines I.4.|.:i of Fig. 9, but on a larger scale.

The burner assembly shown in the drawings comprises in general a wheeled carriage It (Figs. 1 and 2'), an elongated hollowinclined h nd-1e ll secured at its lower end to 1118 frame structure f the carriage and carrying inside thereoi, gas connections to the burner, a valve unit 62 near the upper end of said handle H 'for controlling flow through said connections, a gas distribution block I13 near the lower end oi said handle-,apair of gas mixers :54 connected o a d tributor block, a manifold burner block or head it supported on the forward section of the carriage ill and supplied with a combustible gas mixture from the miners M and with air from the distributor block is, and a series of flame tips 56 connected 1 .0 the burner block 15 and adapted to project their flame cones onto the surface to hedesoaled or otherwise heat treated.

The carriage It comprises a pairof similar side frame members 213,, each having upwardly converging :endsections ,2! and a central horizontal opsect on secured -.to.-th.eends of t e tr 3 members are two axles 23, and mounted on each of these axles is a pair of wheels 24. The side frame members 20, the axles 23 and the wheels 24 thereby form a light, low portable truck.

e Ca e truck is secured to the handle I by means of a pair of inclined side frame members 26 having lower parallel sections 21 straddling the forward inclined end sections 2i of the frame members 20 in substantial inclined alignment therewith, and rigidly secured thereto, as for example, by welding. The intermediate sections 23 of these side frame members 23 converge towards the base of the handle I I, and the upper ends 30 of these side frame members extend in substantially spaced parallel relationship, and are made fast to the handle in a manner to be described. Mounted between these upper frame ends 30 is the gas distributor block I3, supplied with a combustible gas such as acetylene by a pipe connection 32, supplied with a combustion supporting gas, such as oxygen, by a pipe connection 33, and supplied with air by a pipe connection 34. These three pipe connections 32, 33 and 34 are mounted in the handle II, and are respectively controlled by the valve unit I2 near the upper end of said handle. Flexible hose connections (not shown) are provided to this valve unit I2 from the different tanks or other sources of gas supply.

The distributor block I3 is secured to the handle II by means of a flange 4b afiixed to the top of the block, as for example, by studs 4 I, and having a sleeve extension =32 snugly embracing the lower end of the handle II, and secured thereto by screws 43 or other suitable means. The upper ends 30 of the side frame member 25 are made fast to this flange 46 by suitable means, as for example, studs 44.

The distributor block I3 (Figs. 3, 4 and 5) is bored to define the different flow passages. The flow circuit for the acetylene in this block includes an inlet passage 50, to which the supply pipe 32 is fitted, extending from the top of the block partway down, and connecting into the midsection of a manifold passage 5| extending from end to end of said block. To facilitate the machining of this manifold passage 5| in the block I3, this passage is formed by boring right through the block and then closing the ends of the bore, as for example, by suitable sealing brazed plugs 52.

The distributor block I3 has at its lower end two cylindrical branch extensions 53 to which the two mixers M are connected in a manner to be described. Each of these block extensions 53 has an annular groove 53 in which the acetylene is collected and distributed to the mixing chamber of the corresponding mixer I4, as will be de scribed. The acetylene is delivered from the manifold passage 5I to each of these two collecting grooves 54, one in each cylindrical extension 53, by a series of Outlets 55, four being shown for each mixer I 4 circumferentially arranged and extending from said manifold passage 5| through the corresponding block extension 53, and to said collecting groove.

The flow circuit for the oxygen in the distributor block I3 includes an inlet passage 68 to which the supply pipe 33 is connected, extendin from the top of the block partway down, and having two branches 6! diverging downwardly through the main body of the block, and through its extension 53. At their lower ends, each of these oxygen branch passages 5! connects into an outlet opening 62 centrally located with re pec to the acetylene collecting groove 54, and communicating with the mixing chamber of the corresponding mixer I4, as will be described.

Each of the gas mixing units I4 comprises an upper cylindrical shoulder fitting snugly into a corresponding recess 66 in the lower end of the distributor block extension 53, and a neck 6'! fitting snugly into the oxygen outlet 62 in said extension. The mixer I4 is removably clamped to the distributor block extension 53 by means of a nut I0 engaging an annular flange 63 on said mixer I4 and threaded onto said extension. A gas sealing washer 69 fits between mixer I4 and distributor block I3, to prevent intermingling of the two gases, prior to proper mixing, as will be described below.

The shoulder on the mixer I4 has an annular groove II opposite to and in direct communication with the acetylene collecting groove 54, and the q mixer has a central passage I2 connecting with said groove H by a series of inclined ports I3 annularly arranged around said central passage, so that acetylene is delivered to said central passage. The central passage ?2 communicates at its upper end directly with the oxygen outlet 62, so that oxygen is also delivered to said passage. The cross-section of the passage I2 is increased progessively towards the outlet end of the mixer I4, and by the time the oxygen and acetylene reach the outlet 15 of this passage, these gases are thoroughly intermixed. The combustible mixture of gases is delivered by two pipe connections I4 from the two outlets I5 of the mixers I4 to the inlets of the manifold burner head I5.

The distributor block I3 is also employed to distribute air to the burner for the purpose to be further described. To that end, the distributor block I3 has at the top an inlet air passage 15 to which the supply pipe 34 is connected, extending downwardly to the center of a passage 71, which extends from the front to the back of the block, and which is formed by boring completely through the block and sealing the ends of the bore, as for example, by plugging and brazing. The ends of the passage 1'! connect with the ends of two passages 8| extending along the front and rear of the block I3, and formed by boring through from one side of said block, and sealing the ends 82 of said passages 8|, as for example, by plugging and brazing. Each of the passages I 8! has two outlets 83, so that the distributor front face 9|, and plane upper and lower rear angular faces 92. This burner block I5 is removably mounted on the carriage frame desirably by means of a plurality of U-shaped straps 93, three being shown, shaped to conform with the cross-section of the block, and straddling with a snug fit the rear angular faces 92 and the parallel side faces 9?) of the block. The ends of the straps 93 have outwardly extending flange 86. Connected to each of the two end straps 93 and extending across the front face SI of the block I5 at the end is a bracket 95 having an upper end flange extension 93 secured to the corresponding strap flange .94 by a screw 91 and a pair o'filock nuts88. on said screw, and having a ilar lower :end'afiange extension 395 similarly .secured itoJthe corresponding istrap flange 94 by ca screw v1.0.! and looknuts 8. .Themid'dlezstrap =93, instead of having a single bracketssecured. thereto and .extending.:.acmss the. front block facet!) l, has two brackets 1i iltconnected :to thegend flanges 94 of said middle strap respectively by thescrews 9:1, 1H1 l and nuts '98, and engaging :only :the marginal sections of the block face '91. With this :.construction, there is no blocking of the di-fiere-n't outlets leading to said face E9l, or interference with the uniform spacing of these outlets alon the full length of the block it.

The two :rows of screws 9:7 and 510.1 :serve not only as a means for clamping the blockeattach- 'ingxelements 93 95 1.913 to the block 15, but also serve as guards to protect the flame. tips, as will be made more apparent. v

.zSecured to one of the angular sections of each of the two end or outside straps :83 is a bracket Hi5 .inthe vformof an angle havin-g a flange base which is secured to said angular strap section by any suitable means,- and having its other .flange removablysecured toitherearsection 2! of the .corresponding side frame carriagemember 20,, as for example, by a screw [96. Secured to the upper side. section .of each of the two end or outside straps 93 is a second bracket it! in the form ofan anglefhaving a flange base which is secured to said side strap section by any suitable means, and having its other flangeremovably secured to the horizontal top section 22 of the corresponding side frame carriage member 2% as for-examplegbya screw 1138. In this manner, the

burner manifold block 45 can he easily removed for repair or in' caseit is desired to replace it by a lourner block of different length -to-confor-n1 with the width of the-surface to bedescri-bed. in

operative supported position-the front face 3 of :theblock 15 will'extend at an angle with the upper surface :of the-workpiece, so that "the flame 'ltips lfi connected to said blockfaceswill extend iobliquely downwardly towards saidsurfaceat a correct angle, as will hemore fully described The burner manifold :hlcck .15 is formed'with various passages. for the flow of the :combnstible mixture of gases. For thatpurpose, the upper rear angular side 82 (Figs. 7, -12) cfwsaidblock has two inlet :passages M 5- connected- ,to the out,- a let ends .of the two pipe connections 14 leading from the outlets 15 of the two gas-mixers 14. Each of these inlet passage-s H5 transversely extends part way into the block 15 and connects 11117018. passage H5 extending .lBngthWise of the block towards one end -.of said ,block.. At this end of the block E5, there are two short-diverging branch passages Ll] connecting the-passage .115 with two parallel manifoldv passages M3 extend- .ing -.longitudinally of the block, near the front block face 9.! and towards the midsection .Of-Sflld gas mixture along the length of each-manifold 6 \passage rlilfl iand'zthereby eqnalize theirate of d charge from the--dififerent nutletrponts 112d connected thereto, these-massages taper towards the center ofthe blocks, asshownin Fig.7

.The outlet morts 121 are equally spaced along ronesstraight rrowklengthwise-of the block 15, and

two of :such straight rows are formed iii-parallel relationship, j-Inpnderzto form apcontinuousrdame sheet :byzthe conjoint action of the two rows of tips. 5,. the outlet ports 21 in one row are staggered with respeotzto the outletports in the other rc-w, as shown inFEig. 9., -'andthe plane of theatres of the ports 1111,6118 row fiseinclined away from the block towards the :plane of theatres of :thexports in the'other --ro-w., the inclination :of these-two converging axes planes being such that =the-endsofall the flamesare on zaas'rngle straight line parallel torthe longitudinal axis of the block, ias-shownxF-igs. 8 and 1'4.

:Theaips il fi, which are F3111 of the same size and shape, arezdesirably iG'f manner, so that they effectively cool the :burner, :and are comparatively long, pro-jectingasmuch :as inches or more ifrom the aoutletfiace :91 of the hlock'fld These tips 1E :taper .at their outer :ends, and can-therefore be placed ,rfairly close together alongside =o'f eachaother at these ends :toprod-uce :a continuous flame sheet; The tips to are-desirably swaged to shape, this :swaging process --making it possihleitov produce a better tipsan'd consequently a hotter flame. For eflective descalingoperations, the flames rproduced by' these tips rlafi are desirably (of these -called:semi-hlunt type.

.Air is circulated through different passages in the manifold block tenor-cooling purposes, and is projected against the surface of the workpiece being treated to "remove the slag loosened or formed :hytheaetion ofthe flames. The air circuit through 'the'block It comprises four inlet :holes lfi' l'extend from the manifold passage to the front block i-face 91L The two outside inlet passages I30 connect transversely of the block :into two passages ['35 respectively, extending longitudinally alon the block 1 5 towards their ends. At the ends of the block 15, these passages 1'35 connect-by short transverse passages it with the end of a manifold'passage. l33extending near the front block face '91 along the length of said block on the side "thereof opposite the air manifold passage 133. A row of small outlet air holes 16%! extend from the manifold passage Hate the 'front block face .91.

To facilitate machining operations-in forming the different air passages in'the burner block l5, some of theair passages are formed 'by .drilling or boring from the faces and ends of the block t5, and'sealin'g the ends of these passages at these block' faces and ends by plugs Ml de fsirably brazed in. The tworows of outletwairiholes I34 and M are parallel, and extend along the'block Iii-on opposite sides of'the vtwo rows oi m'ixed gas cut pass to the pipe connections 32 and 33.

lets I2l. These air holes I34 and I40 in the two rows extend substantially parallel, and project the air against the workpiece in planes substantially parallel to the plane of the flame sheet. Due to the comparatively long distance between the air holes I34 and I40, and the surface of the workpiece, the streams from the holes in each row merge before they reach said surface, and strike said surface as a continuous curtain stream, so that a more efiective sweeping action by the ejected air is assured.

The oxygen and acetylene for the gas mixture, and the air for the cooling and sweeping operation is supplied through the respective valves in the valve unit I2 (Fig. 1) at the upper end of the handle I I. This valve unit comprises a combination of a quick shut-off valve and valve assembly similar to that shown in copending application Serial No. 597,300. Member I5!) is a lever which must be pressed down before gas can This lever I50 is locked down by a catch in the handle I I. In the event of a backfire or a flash-back, the operator may quickly shut off the supply of gas and remove the danger of serious damage. The quick shut-off valve is also used to shut off the gas when work is stopped for some reason. Once the two valves I5I controlling flow of the two connections 32 and 33 respectively are adjusted, the quick shut-off valve may be used for starting and stopping the burner without the necessity of readiusting these two valves.

By means of the carriage burner mounting of the present invention, the tips I6 are properly spaced above the workpiece and at the correc angle.

These tips I6 are efi'ectively protected a ainst iniury in the front by the three adiustable long guard screws 91 and in the rear by the three adjustable short guard screws I Ell. With this guard arrangement any abrupt bumps in the formation of the surface being treated. or any raised member in the path of the tips I6 will not strike these tips. The burner manifold blocks l5 may be built in different lengths having the same cross-sections and same size tips I6 attached thereto. and these blocks may be interchangeably mounted on the same carriage according to the width of the surface to be descaled. For examp e. the burner may be built in three sizes, 8". 10" and 12'. The number of tips I6 in each of these burners varies according to the size of he burner. For instance, a 12" burner may have 33 tins in o e row and 32 tips in the other row, making a total of 65 tips.

To change the burner size, it is only necessary to remove the four screws M6 and ma attaching the bracket assembly of the burner block I5 to the carriage frame, and to loosen the six union connections between the pipes 14, 85 and the burner manifold block inlets II 5, H9 and I311. The screw plugs closing the ends of the passages in the burner manifold block I5 may be remove for cleaning these passages. Since the volume of acetylene used in the burner is relatively high, a better mixture of these gases is obtained with less danger of back-firing and flash-back by using two mixers.

The relatively long distance that the gas 'travels in the tips I6 prevents the gas from becoming turbulent, and results in a smooth gas flow and stable flame cones.

As many changes can be made in the above apparatus, and many apparently widelydifierent embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanyin drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

l. A burner for progressively heating a metal member along the surface thereof, said burner including a burner head having two separate parallel passages for an oxygen-acetylene mixture and two rows of tips, each row leading from a separate passage, and the tips of each row being slightly inclined toward those of the other row and being of such length as to align the outlet ends of all of said tips in substantially a single straight line extending lengthwise of said burner head' 2. A burner for progressively heating a metal member along the surface thereof, said burner including a burner head having two separate parallel passages for an oxygen-acetylene mixture and two rows of tips, each row leading from a separate passage, and the tips of each row being slightly inclined toward those of the other row, the outlet ends of the tips of the two rows being arranged alternately and closely spaced together in substantially a single straight line to cause the flames from all of the tips to be projected in substantially the same direction to form substantially a single continuous sheet of flame.

3. A burner having an elongated body member provided with a pair of passages extending lengthwise thereof, a pair of oxygen-acetylene mixers, means for delivering the gas mixture from one mixer to one end of one of said passages, and means for delivering gas mixture from the other mixer to one end of the other passage, and means including two rows of elongated tips, each row being separately supplied with gas mixture from said passages, the tips of the two rows being in planes at a small angle to each other and the delivery ends of the tips of both rows being closely juxtaposed to deliver gas into substantially a single plane extending lengthwise of said body member.

4. A burner having an elongated body member provided with a pair of passages extending lengthwise thereof, a pair of oxygen-acetylene mixers. one of said mixers being connected to one end of said body for feeding gas mixture to one end of one of said passages, and the other mixer being connected to the other end of said body for feeding gas mixture to the other end of the other passage, and two rows of elongated tips, each row being separately supplied with gas mixture from said passages, and the tips of the two rows being in planes at a slight angle to each other and the ends of said tips being substantially in a single row and alternately arranged to deliver gas mixture from all of said tips into substantially a single plane extending lengthwise of said body member.

5. A burner having an elongated body member provided with a pair of passages extending lengthwise thereof, said passages being substantially in alinement, means for delivering an oxygen-acetylene mixture to the outer ends of both passages, and means including two rows of elongated tips separately supplied with gas from said passages, the tips of the two rows being in planes slightly inclined toward each other and ;theoutletends of all oi said tips being substan- 9 tially in a single straight line extending lengthwise of said body member.

6. A burner having an elongated body member provided with a pair of passages extending lengthwise thereof and each having a row of delivery tips inclined toward those of the other row to align the outlet ends of all of said tips substantially in a single straight line, said passages being substantially parallel and of progressively decreasing diameter inwardly from the outer end thereof, and means for delivering an oxygen-acetylene mixture to the outer ends of both passages.

7. A burner having an elongated body portion provided with a pair of mixture passages extending lengthwise thereof, two rows of tips, one leading from one of said passages and the other leading from the other of said passages, the tips of one of said rows being slightly inclined to those of the other row, and the outlet ends of the tips of both rows being substantially in a single straight line, a gas mixer, and means for connecting said gas mixer to one end of one of each of said passages.

8. A burner for progressively heating a metal member along the surface thereof, said burner including a burner head having two separate parallel passages for an oxygen-acetylene mixture and two rows of tips, each row leading from a separate passage, and the tips of each row being slightly inclined toward those of the other row and of such length that the outlet ends of said tips are disposed in substantially a single straight line, said burner head also having a passage extend ng lengthwise thereof and provided with outlet openings in the face bearing said tips, and means for delivering air through said last mentioned passage.

9. In an apparatus for heat treating a metal surface having a carriage, a handle connected thereto, a gas distribution block carried by said handle, conduits extending lengthwise of said handle and connected to said block for supplying separately oxygen, acetylene and air thereto, the combination of a pair of mixers connected to said block for receiving and mixing oxygen and acetylene to form a combustible gas mixture, a burner having an elongated body member secured to said carriage and provided with a pair of passages for said gas mixture and an air passage extend ng lengthwise thereof, conduit means connecting one of said mixers with each of said gas passages and for supplying-air to said air passages, two rows of elongated tips carried by one face of said elongated body member, the tips of each row being supplied with gas mixture from one of said gas passages and being inclined toward those of the other row and alternately arranged to align the outlet ends of the tips in substantially a single straight line extending lengthw se of said body member, and a row of air outlets from said air passage in the face of said body member bearing said tips.

10. In an apparatus for heat treating a surface having a carriage, a handle for propelling said carriage and having separate passages extending lengthwise thereof for oxygen and for a combustible gas, the combination of a pair of gas mixers secured to said handle and each connected to both of said passages, a burner block on said carriage having a plurality of manifold passages extending lengthwise thereof and provided with outlets along the length thereof, means connecting one of said mixers to one of said passages and means for connecting the other of said mixers to another of said passages, and

means including converging elongated tips to deliver gas mixture from each of said outlets into substantially a single plane extending lengthwise of said burner block.

11. In an apparatus as defined in claim 10, in which said manifold passages are in axial alignment and are of progressively decreasing crosssectional area inwardly from the gas receiving end.

12. An apparatus for heat treating a metal surface, including a portable frame, a burner body extending transversely of said frame and having a row of nozzles directed toward the surface to be treated, means for supporting said frame and the burner nozzles carried thereon in spaced relation to the surface to be treated, said supporting means being located both in advance and behind the burner body for effecting relative movement thereof with respect to the surface to be treated, and a plurality of guard means for protecting the tips of said burner nozzles, each of said guard means being supported by said frame adjacent to one of said burner nozzles but spaced therefrom and directed toward the surface to be treated, the terminal portion of each of said guard means being located at a point closer to the surface to be treated than the tip of the adjacent burner nozzle.

13. An apparatus as defined in claim 12 in which said guard means are adjustable toward and away from the surface to be treated.

14. An apparatus as defined in claim 12 in which a plurality of pairs of guard means are supported by said frame with the two guards of each pair on opposite sides of one of said burner nozzles adjacent thereto but spaced therefrom and directed toward the surface to be treated, the terminal portions of each of said guard means being located at a point closer to the surface to be treated than the tip of the adjacent burner nozzle.

CHESTER MOTT. ALFRED F. CHOUINARD. MITCHELL A. TYLUTKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 1,590,195 Kerr June 29, 1926 1,899,626 Miller Feb. 28, 1933 1,982,518 Howard Nov. 27, 1934 2,018,259 Hartley Oct. 22, 1935 2,031,583 Anderson Feb. 25, 1936 2,058,388 Rendleman Oct. 20, 1936 2,130,261 Bucknam Sept. 13, 1938 2,178,451 Jones et al Oct. 31, 1939 2,181,937 Eskridge Dec. 5, 1939 2,267,405 Jones et al. Dec. 23, 1941 2,282,397 Deck May 12, 1942 2 295,522 Shorter Sept. 8, 1942 2,295,701 Wagner Sept. 15, 1942 2,337,087 Deck Dec. 21, 1943 2,398,884 Crowe Apr. 23, 1946 2,418,533 Walker Apr. 8, 1947 2,441,474 Dietrich May 11, 1948 2,442,437 Robbins et a1. June 1, 1948 FOREIGN PATENTS Number Country Date 726,268 France Feb. 29, 1932 818,357 France June 14, 1937- 

